The present invention relates to a current-source arrangement comprising:
a plurality of transistor configurations for generating a plurality of substantially equal currents, and PA1 correction means for reducing the mutual deviation in the currents from the transistor configurations. PA1 the number of transistor configurations is at least one larger than the required number of currents, PA1 each transistor configuration comprises a control transistor whose control voltage is adjustable to supply an adjustable first current, and PA1 the correction means are adapted to make the current from each transistor configuration equal to a reference-current in accordance with a cyclic pattern by adjusting the control voltage of the control transistor of the relevant transistor configuration.
The invention also relates to a digital-to-analog converter comprising such an arrangement.
Such an arrangement is know from U.S. Pat. No. 4,573,005. In this arrangement the correction means comprise a precision-current-mirror circuit in which the current from one transistor configuration is applied to the input as a reference-current and the current from another transistor configuration is applied to the at least one output in accordance with a cyclic pattern. The difference between the reference-current and the current from the other transistor configuration then appears on this output, said difference being used to correct the last mentioned current in such a way that it is in better compliance with the reference-current.
A disadvantage of this arrangement is that the precision-current-mirror circuit must be arranged in series with the transistor configuration and its load so that the known current-source arrangement requires a comparatively high supply voltage.